Stephenson County Water Quality
Stephenson County, Illinois: one city report built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.
Highest result for each contaminant
One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.
Perfluorooctanesulfonic acid (PFOS)FREEPORT4.0 ng/L federal MCL (2024) · US EPA14 ng/L
- FREEPORT14 ng/LSample date: 2023-07-18 to 2024-07-29
Lead (90th percentile)FREEPORT15 µg/L federal action level · US EPA3.6 µg/L
- FREEPORT3.6 µg/LMonitoring period: 2026–2028 (still open)
29 substances tested, none detected in this systemShow
Tested in this system: FREEPORT
- 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
- 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
- 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
- 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
- 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
- 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
- Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
- Lithium
- N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
- N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
- Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
- Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
- Perfluoro-3-methoxypropanoic acid (PFMPA)
- Perfluoro-4-methoxybutanoic acid (PFMBA)
- Perfluorobutanesulfonic acid (PFBS)
- Perfluorobutanoic acid (PFBA)
- Perfluorodecanoic acid (PFDA)
- Perfluorododecanoic acid (PFDoA)
- Perfluoroheptanesulfonic acid (PFHpS)
- Perfluoroheptanoic acid (PFHpA)
- Perfluorohexanesulfonic acid (PFHxS)
- Perfluorohexanoic acid (PFHxA)
- Perfluorononanoic acid (PFNA)
- Perfluorooctanoic acid (PFOA)
- Perfluoropentanesulfonic acid (PFPeS)
- Perfluoropentanoic acid (PFPeA)
- Perfluorotetradecanoic acid (PFTA)
- Perfluorotridecanoic acid (PFTrDA)
- Perfluoroundecanoic acid (PFUnA)
Cities ranked by the records
Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.
0of 1 city above the 15 µg/L action level
Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.
Lead in IllinoisLargest water systems
- FreeportFREEPORT · IL177020023,930 served
Frequently asked
How does Stephenson County tap water compare across cities?
PurityMap ranks 1 city in Stephenson County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Freeport's main water system: FREEPORT · PWSID IL1770200 · Purity Score 53 (Poor) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.
How many Stephenson County cities have PFAS above the federal limit?
1 city of 1 had at least one regulated PFAS (PFOA, PFOS or PFHxS) measured above the 2024 federal limit in EPA's UCMR 5 testing, including Freeport (PFOS 14 ng/L). PFAS were detected at any level in 1.
Is there lead in Stephenson County tap water?
Utilities report lead as a 90th-percentile result from home taps. 1 of 1 Stephenson County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.
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